Waste type. Waste composition affects the rate, quality, and quantity of gas. Site operations. Waste compaction and rapid infilling will shorten aerobic ...
LANDFILL GAS EMISSIONS FROM A BRAZILIAN MSW LANDFILL F.J. MACIEL AND J.F.T. JUCÁ Department of Civil Engineering, Federal University of Pernambuco (UFPE), Brazil
SUMMARY: Landfill gas (LFG) emission from the final cover layer of MSW landfill is considered an important parameter for preventing local, national, and global air pollution. The study on LFG emissions at Muribeca`s Landfill involved field and laboratory experiments. Field investigation was carried out using a static flux chamber methodology in order to evaluate gas percolation through the cover layer. Gas flux rates ranging from 10-7 to 10-6 m3/s were determined depending on cover soil parameters. Gas concentrations, pressure, and temperature were also analysed in this study. Laboratory tests were realized in order to determine the soil gas permeability for different degrees of saturation and compaction densities. A gas liberation reduction (10 times) would have been expected if the cover layer had been compacted near the maximum dry density. 1. INTRODUCTION Organic matter decomposition processes in MSW landfill produce toxic gases that can directly affect the environment. Over the landfill life cycle, aerobic and anaerobic degradation processes will be established according to the presence or absence of oxygen (O2) in waste mass, influenced by local climate conditions and cover layer efficiency. Anaerobic decomposition process takes place as most part of the oxygen were consumed by aerobic activity. In an effort to create this environment, the waste should have excellent cover and drainage systems in order to prevent from local climate variations. The gas produced in this phase is called landfill gas (LFG) composed basically of methane (CH4) and carbon dioxide (CO2). Both of these gases are considered “Greenhouse Gases”, whose atmospheric accumulation can directly interfere in the world climate changes. In addition, the LFG is dangerous for landfill operators and also surrounding population due to its flammability and asphyxiating characteristics. Table 1. LFG typical composition and individual gas properties (adapted Gandolla et. al., 1997). Component: CH4 Typical concent. (% vol.) 45-60 Density (kg/m3) 0.717 3 Calorific potential (kJ/m ) 35,600 Explosive Limit (% vol.) 5-15 Water solubility (g/l) 0.0645 * General properties O, C, NT, A, F
CO2 35-50 1.977 ----1.688 O, C, A
N2 0-10 1.250 ----0.019 O, C
O2 0-4 1.429 ----0.043 O, C
* - O = odorless, C = colorless, NT = non-toxic, T = toxic, F = flammable, A = asphyxiant
CO H2S
